mirror of https://github.com/GNOME/gimp.git
521 lines
11 KiB
C
521 lines
11 KiB
C
/* The GIMP -- an image manipulation program
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* Copyright (C) 1995 Spencer Kimball and Peter Mattis
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <stdio.h>
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#include <glib-object.h>
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#include "libgimpmath/gimpmath.h"
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#include "base-types.h"
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#include "gimphistogram.h"
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#include "gimplut.h"
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#include "lut-funcs.h"
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/* ---------- Brightness/Contrast -----------*/
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typedef struct B_C_struct
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{
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gdouble brightness;
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gdouble contrast;
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} B_C_struct;
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static gfloat
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brightness_contrast_lut_func (B_C_struct *data,
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gint nchannels,
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gint channel,
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gfloat value)
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{
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gfloat nvalue;
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gdouble power;
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/* return the original value for the alpha channel */
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if ((nchannels == 2 || nchannels == 4) && channel == nchannels -1)
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return value;
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/* apply brightness */
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if (data->brightness < 0.0)
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value = value * (1.0 + data->brightness);
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else
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value = value + ((1.0 - value) * data->brightness);
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/* apply contrast */
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if (data->contrast < 0.0)
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{
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if (value > 0.5)
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nvalue = 1.0 - value;
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else
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nvalue = value;
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if (nvalue < 0.0)
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nvalue = 0.0;
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nvalue = 0.5 * pow (nvalue * 2.0 , (double) (1.0 + data->contrast));
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if (value > 0.5)
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value = 1.0 - nvalue;
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else
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value = nvalue;
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}
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else
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{
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if (value > 0.5)
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nvalue = 1.0 - value;
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else
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nvalue = value;
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if (nvalue < 0.0)
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nvalue = 0.0;
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power = (data->contrast == 1.0) ? 127 : 1.0 / (1.0 - data->contrast);
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nvalue = 0.5 * pow (2.0 * nvalue, power);
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if (value > 0.5)
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value = 1.0 - nvalue;
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else
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value = nvalue;
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}
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return value;
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}
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GimpLut *
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brightness_contrast_lut_new (gdouble brightness,
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gdouble contrast,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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brightness_contrast_lut_setup (lut, brightness, contrast, n_channels);
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return lut;
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}
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void
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brightness_contrast_lut_setup (GimpLut *lut,
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gdouble brightness,
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gdouble contrast,
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gint n_channels)
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{
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B_C_struct data;
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data.brightness = brightness;
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data.contrast = contrast;
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gimp_lut_setup (lut, (GimpLutFunc) brightness_contrast_lut_func,
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(gpointer) &data, n_channels);
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}
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/* ---------------- invert ------------------ */
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static gfloat
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invert_lut_func (gpointer unused,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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/* don't invert the alpha channel */
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if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
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return value;
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return 1.0 - value;
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}
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GimpLut *
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invert_lut_new (gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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invert_lut_setup (lut, n_channels);
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return lut;
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}
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void
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invert_lut_setup (GimpLut *lut,
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gint n_channels)
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{
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gimp_lut_setup_exact (lut, (GimpLutFunc) invert_lut_func,
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NULL , n_channels);
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}
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/* ---------------- add (or subract)------------------ */
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static gfloat
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add_lut_func (gdouble *amount,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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/* don't change the alpha channel */
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if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
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return value;
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return (value + *amount);
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}
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GimpLut *
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add_lut_new (gdouble amount,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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add_lut_setup (lut, amount, n_channels);
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return lut;
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}
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void
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add_lut_setup (GimpLut *lut,
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gdouble amount,
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gint n_channels)
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{
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gimp_lut_setup (lut, (GimpLutFunc) add_lut_func,
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(gpointer) &amount, n_channels);
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}
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/* ---------------- intersect (MIN (pixel, value)) ------------------ */
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static gfloat
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intersect_lut_func (gdouble *min,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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/* don't change the alpha channel */
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if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
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return value;
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return MIN (value, *min);
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}
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GimpLut *
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intersect_lut_new (gdouble value,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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intersect_lut_setup (lut, value, n_channels);
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return lut;
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}
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void
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intersect_lut_setup (GimpLut *lut,
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gdouble value,
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gint n_channels)
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{
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gimp_lut_setup_exact (lut, (GimpLutFunc) intersect_lut_func,
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(gpointer) &value , n_channels);
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}
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/* ---------------- Threshold ------------------ */
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static gfloat
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threshold_lut_func (gdouble *min,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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/* don't change the alpha channel */
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if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
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return value;
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if (value < *min)
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return 0.0;
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return 1.0;
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}
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GimpLut *
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threshold_lut_new (gdouble value,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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threshold_lut_setup (lut, value, n_channels);
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return lut;
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}
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void
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threshold_lut_setup (GimpLut *lut,
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gdouble value,
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gint n_channels)
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{
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gimp_lut_setup_exact (lut, (GimpLutFunc) threshold_lut_func,
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(gpointer) &value , n_channels);
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}
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/* ------------- levels ------------ */
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typedef struct
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{
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gdouble *gamma;
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gint *low_input;
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gint *high_input;
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gint *low_output;
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gint *high_output;
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} levels_struct;
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static gfloat
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levels_lut_func (levels_struct *data,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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gdouble inten;
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gint j;
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if (n_channels == 1)
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j = 0;
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else
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j = channel + 1;
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inten = value;
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/* For color images this runs through the loop with j = channel +1
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* the first time and j = 0 the second time
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*
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* For bw images this runs through the loop with j = 0 the first and
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* only time
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*/
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for (; j >= 0; j -= (channel + 1))
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{
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/* don't apply the overall curve to the alpha channel */
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if (j == 0 && (n_channels == 2 || n_channels == 4)
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&& channel == n_channels -1)
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return inten;
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/* determine input intensity */
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if (data->high_input[j] != data->low_input[j])
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inten = ((gdouble) (255.0 * inten - data->low_input[j]) /
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(gdouble) (data->high_input[j] - data->low_input[j]));
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else
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inten = (gdouble) (255.0 * inten - data->low_input[j]);
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if (data->gamma[j] != 0.0)
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{
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if (inten >= 0.0)
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inten = pow ( inten, (1.0 / data->gamma[j]));
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else
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inten = -pow (-inten, (1.0 / data->gamma[j]));
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}
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/* determine the output intensity */
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if (data->high_output[j] >= data->low_output[j])
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inten = (gdouble) (inten * (data->high_output[j] - data->low_output[j]) +
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data->low_output[j]);
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else if (data->high_output[j] < data->low_output[j])
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inten = (gdouble) (data->low_output[j] - inten *
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(data->low_output[j] - data->high_output[j]));
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inten /= 255.0;
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}
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return inten;
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}
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GimpLut *
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levels_lut_new (gdouble *gamma,
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gint *low_input,
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gint *high_input,
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gint *low_output,
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gint *high_output,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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levels_lut_setup (lut, gamma, low_input, high_input,
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low_output, high_output, n_channels);
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return lut;
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}
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void
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levels_lut_setup (GimpLut *lut,
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gdouble *gamma,
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gint *low_input,
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gint *high_input,
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gint *low_output,
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gint *high_output,
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gint n_channels)
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{
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levels_struct data;
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data.gamma = gamma;
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data.low_input = low_input;
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data.high_input = high_input;
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data.low_output = low_output;
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data.high_output = high_output;
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gimp_lut_setup (lut, (GimpLutFunc) levels_lut_func,
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(gpointer) &data, n_channels);
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}
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/* --------------- posterize ---------------- */
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static gfloat
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posterize_lut_func (gint *ilevels,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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gint levels;
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/* don't posterize the alpha channel */
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if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
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return value;
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if (*ilevels < 2)
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levels = 2;
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else
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levels = *ilevels;
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value = RINT (value * (levels - 1.0)) / (levels - 1.0);
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return value;
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}
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GimpLut *
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posterize_lut_new (gint levels,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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posterize_lut_setup (lut, levels, n_channels);
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return lut;
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}
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void
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posterize_lut_setup (GimpLut *lut,
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gint levels,
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gint n_channels)
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{
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gimp_lut_setup_exact (lut, (GimpLutFunc) posterize_lut_func,
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(gpointer) &levels , n_channels);
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}
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/* --------------- equalize ------------- */
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typedef struct
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{
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GimpHistogram *histogram;
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gint part[5][257];
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} hist_lut_struct;
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static gfloat
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equalize_lut_func (hist_lut_struct *hlut,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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gint i = 0;
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gint j;
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j = (gint) (value * 255.0 + 0.5);
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while (hlut->part[channel][i + 1] <= j)
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i++;
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return i / 255.0;
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}
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GimpLut *
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eq_histogram_lut_new (GimpHistogram *histogram,
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gint n_channels)
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{
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GimpLut *lut;
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lut = gimp_lut_new ();
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eq_histogram_lut_setup (lut, histogram, n_channels);
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return lut;
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}
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void
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eq_histogram_lut_setup (GimpLut *lut,
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GimpHistogram *hist,
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gint n_channels)
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{
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gint i, k, j;
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hist_lut_struct hlut;
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gdouble pixels_per_value;
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gdouble desired;
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gdouble sum, dif;
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/* Find partition points */
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pixels_per_value = gimp_histogram_get_count (hist, 0, 255) / 256.0;
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for (k = 0; k < n_channels; k++)
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{
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/* First and last points in partition */
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hlut.part[k][0] = 0;
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hlut.part[k][256] = 256;
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/* Find intermediate points */
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j = 0;
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sum = (gimp_histogram_get_channel (hist, k, 0) +
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gimp_histogram_get_channel (hist, k, 1));
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for (i = 1; i < 256; i++)
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{
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desired = i * pixels_per_value;
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while (sum <= desired)
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{
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j++;
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sum += gimp_histogram_get_channel (hist, k, j + 1);
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}
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/* Nearest sum */
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dif = sum - gimp_histogram_get_channel (hist, k, j);
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if ((sum - desired) > (dif / 2.0))
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hlut.part[k][i] = j;
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else
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hlut.part[k][i] = j + 1;
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}
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}
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gimp_lut_setup (lut, (GimpLutFunc) equalize_lut_func,
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(gpointer) &hlut, n_channels);
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}
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